CD31

• CD31 expression in epithelioid hemangioendothelioma of the liver.
• CD31 expression in epithelioid hemangioendothelioma of the liver.
• CD31 expression in epithelioid hemangioendothelioma of the liver.
• CD31 expression in epithelioid hemangioendothelioma of the liver.
• CD31 expression in epithelioid hemangioendothelioma of the liver.
• CD31 expression in epithelioid hemangioendothelioma of the liver.
• CD31 expression in epithelioid hemangioendothelioma of the liver.
• Membranous CD31 expression in cutaneous epithelioid angiosarcoma.
• Membranous CD31 expression in cutaneous epithelioid angiosarcoma.
• Membranous CD31 expression in cutaneous epithelioid angiosarcoma.
• CD31 expression in spindle cell angiosarcoma metastatic to the lung.
• CD31 expression in spindle cell angiosarcoma metastatic to the lung.
• CD31 expression in spindle cell angiosarcoma metastatic to the lung.
• CD31 expression in spindle cell angiosarcoma metastatic to the lung.
• CD31 expression in vascular and lymphatic endothelium in a benign lymph node.
• CD31 is often expressed by normal histiocytes.
• CD31 is often expressed by normal histiocytes.

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Synonyms

• PECAM-1

Staining Pattern

• Membranous

Expression in Normal Tissues

• Highly sensitive and specific for endothelium of blood vessels and lymphatics
• May be expressed by normal histiocytes

Expression in Neoplastic Entities

Benign

Tumor name	% Positive Staining (Sensitivity)	Number of Cases	Specificity	Comments
Hemangioma (all types)	100%	13
Lymphangioma	91%	33

Intermediate/Uncertain Malignant Potential

Tumor name	% Positive Staining (Sensitivity)	Number of Cases	Specificity	Comments
Atypical vascular lesion (AVL) of breast (post-radiation)
Hemangioendothelioma (all types)
Epithelioid sarcoma-like hemangioendothelioma (Note: negative for CD34)

Malignant

Tumor name	% Positive Staining (Sensitivity)	Number of Cases	Specificity	Comments
Angiosarcoma

Expression in Non-Neoplastic Entities

• Vascular malformations

Pertinent Negatives

CD31 is typically NOT expressed in the following:

• Most carcinomas (NOTE: carcinomas can sometimes express CD31)

Practical Uses / Panels

Can be used to indicate the vascular origin of tumors

Common Pitfalls

• Collections of CD31 positive histiocytes may be mistaken for a vascular neoplasm.
• Plasma cells and some activated T- and B- lymphocytes may also exhibit moderate to strong membranous reaction.

References

Bhawan J, Silva C, Taungiaruwinai WM. Inconsistent immunohistochemical expression of lymphatic and blood endothelial cell markers in cutaneous lymphangiomas. J Cutan Pathol 2013 Sep;40(9): 801-6.